In a large saute pan over high heat, warm the oil. Add the onions and rosemary, and cook until soft and translucent, about 5 minutes. Add butter and lower heat and continue to caramelize for about 15 minutes. Season with salt and pepper and set aside.
Spread the pizza dough with the onion mixture and scatter Gorgonzola over top. Bake in a pizza oven or a preheated 400 degree oven until lightly golden and the crust is browned, about 20 minutes. Cut into wedges and serve.
Pour the water onto a medium--sized mixing bowl and add the yeast, stirring with a fork until dissolved. The water should turn a light beige color. Add 1 cup of flour and the salt. Mix thoroughly with a wooden spoon. Add the second cup of flour and repeat. The dough should start coming away from the sides of the bowl, forming a soft, sticky mass. Take the last cup of flour and sprinkle over a clean, dry work surface and flour your hands well.Take the dough from the bowl and begin to work in the additional flour a little at a time. Use the heel of your hand to knead the dough and push across the work surface, clenching the dough with your fist and twisting it over. Use a dough scraper to help gather any wet dough that sticks to the surface while you are kneading. Also only add as much flour as it takes to keep the dough from sticking to your hands. When the dough no longer feels sticky, push the heel of your hand down into it and hold it there for 10 seconds. If the dough comes up clean, it's ready. If it sticks you will have to knead it a bit more.
Lightly oil a 2 quart bowl with vegetable oil, and roll the ball of dough around the bowl to coat it with a thin film of oil, then tightly seal the bowl with plastic wrap. Keep in a warm place, and let the dough rise for 30 to 45 minutes. When dough doubles in size, remove from bowl and punch it down with your fist to deflate, then knead it again for about a minute. Dough is now ready to stretch into a round, or press into a pizza pan.
Note: If you have a food processor with a dough hook attachment, you can make the dough much faster. Start by adding the yeast and water first and mixing well. Then add all the flour and salt and mix into a ball. Then rise the dough.